In the automotive industry, there is an ongoing effort to improve automobile quality while decreasing cost. In the field of automobile frame assemblies, there is an effort to increase frame stiffness and reduce cost. In the past, stiffness was achieved by adding more material to the frame and by providing more, thicker crossmembers. However, as more material is added, there is an incremental material cost involved. As a result, frame assemblies become heavier and bulkier and cost more to ship and handle. There is also a detriment in fuel economy with increased vehicle weight. Other factors to be considered are part complexity; as the number of components in a frame assembly increase, so does the assembly time. Increased assembly time is ultimately passed along to the consumer in increased prices. The present objective is to increase stiffness, decrease the number of parts and improve shipping and handling of the frame assemblies.
Current frame assemblies typically include a pair of frame rails, a front subframe, a rear subframe, and various crossmembers and support assemblies. Specifically, the rear suspension support assembly provides a mounting structure for the rear suspension system. There are a large number of parts that make up a rear suspension support assembly. Therefore, it is desirable to improve the current rear suspension support assemblies by reducing the number of parts that are included in the assembly.
In the conventional automobile, the vehicle frame rails are generally a pair of frame rails that extend in a longitudinal direction to the vehicle body while the crossmember of the rear suspension support assembly spans between the left and right frame rails in a transverse direction to the vehicle body. The crossmember of a rear suspension support assembly is rigidly mounted to the frame rails and is generally perpendicular to the vehicle frame rails. There are a number of ways that the crossmember can be attached to the frame rails, however the most common methods are either welding or by incorporating fasteners. There is a deficiency with this design, however, in that diagonal stiffness is deficient since the crossmembers form a 90.degree. angle to the vehicle frame rails. Although the conventional design provides for good lateral stiffness, the design is compromised in its ability to transfer diagonal forces. Each crossmember is attached to a frame rail at one point, this single point attachment acts as a hinge when subject to diagonal loads. When there is a disproportionate load distributed between the left and right vehicle frame rails resulting in a diagonal force, a conventional rear suspension support assembly design will allow the frame rails to translate. Therefore, instead of transferring the diagonal load, a conventional rear suspension support assembly will yield.
Shipping costs for transporting frame assemblies can be reduced by increasing the number of frame assemblies that are stacked with each shipment, a limiting factor being the height of each frame assembly. If the frame assembly has a low-hanging component, the number of frame members which can be stacked and shipped is reduced. In some cases, the lowest hanging member of an automobile frame assembly is the track bar bracket. This results in an increase in shipping costs which are ultimately absorbed by the consumer. Therefore, there is a need for an improved rear suspension support assembly which provides for more efficient stacking of automobile vehicle frame assemblies.